Occurrence and molecular characterization of Potato spindle tuber viroid(PSTVd) isolates from potato plants in North China

China is the largest potato producing country worldwide,with this crop representing the fourth largest staple food crop in China.However,the steady presence of Potato spindle tuber viroid(PSTVd) over the past five decades has a significant economic impact on potato production.To determine why PSTVd control measures have been ineffective in China,more than 1 000 seed potatoes collected between 2009 and 2014 were subjected to PSTVd detection at the Supervision and Testing Center for Virus-free Seed Potatoes Quality,Ministry of Agriculture,China.A high PSTVd infection rate(6.5%) was detected among these commercial seed potatoes.Some breeding lines of potato collected from 2012 to 2015 were also tested for PSTVd infection,revealing a high rate of PSTVd contamination in these potato propagation materials.Furthermore,comparison of the full-length sequences of 71 different Chinese PSTVd isolates revealed a total of 74 predominant PSTVd variants,which represented 42 different sequence variants of PSTVd.Comparative sequence analysis revealed 30 novel PSTVd sequence variants specific to China.Comprehensive phylogenetic analysis uncovered a close relationship between the Chinese PSTVd sequence variants and those isolated from Russia.It is worth noting that three intermediate strains and six mild strains were identified among these variants.These results have important implications for explaining the ineffective control of PSTVd in China and thus could serve as a basic reference for designing more effective measures to eliminate PSTVd from China in the future.     

PSTVd，PLRV和PVS在马铃薯试管苗不同部位继代积累规律研究

 为研究病毒和类病毒在马铃薯试管苗不同部位的积累规律,利用实时荧光定量PCR和DAS-ELISA两种方法检测马铃薯纺锤块茎类病毒(Potato spindle tuber viroid, PSTVd)、马铃薯卷叶病毒(Potato leafroll virus, PLRV)和马铃薯S病毒（Potato virus S, PVS）在马铃薯试管苗基部和顶端继代培养5代（继5代）后的含量。结果表明：PSTVd,PLRV和PVS在马铃薯试管苗常规组织培养过程中是逐代传递的,其在马铃薯试管苗顶端和基部的积累规律存在显著的品种差异,分别供试的7个品系中,存在PSTVd顶端积累和基部积累效应的各3个品系,存在PLRV顶端积累和基部积累效应的分别为4个和2个品系,存在PVS顶端积累和基部积累效应的分别为3个和2个品系,其中PSTVd的顶端积累效应最强为基部的4倍;同一马铃薯品系的顶端和基部对不同病毒和类病毒的积累趋势相对一致。实时荧光定量PCR是一种灵敏度很高的定量检测马铃薯病毒和类病毒的方法。     

我国在防治马铃薯类病毒病中存在的问题及防治对策

马铃薯纺锤块茎类病毒病(Potato spindle tuber viroid,PSTVd)是威胁我国马铃薯生产的重要病害之一,已经给我国的马铃薯生产造成了严重影响,导致了经济损失.在防治该病害方面存在着脱除难,检测不到位,脱毒种薯质量控制体系不健全,监管力度不够等问题.今后,要加大PSTVd脱毒技术的研究,选用健康的...     

NASH技术和R-PAGE技术在马铃薯类病毒检测上的应用

往复聚丙烯酰胺凝胶电泳 (R- PAGE)和核酸斑点杂交技术 (NASH)是检测马铃薯块茎类病毒(PSTVd)的主要技术 ,利用这两种方法 ,进行马铃薯脱毒试管苗的类病毒检测。结果表明 ,两种方法得到了相似的检测结果。通过试验 ,比较两种检测方法在检测灵敏度、操作性、检测量等方面的优缺点和可行性。NASH方法具有较高的灵敏性 ,适合大批量样品检测和异地取样。而 R- PAGE可区分类病毒的强弱系 ,对试验条件和技术条件要求低于 NASH方法     

Study on PCR rapid molecular detection technique of Meloidogyne vitis

Meloidogyne vitis is a new root-knot nematode parasitic on grape root in Yunnan Province, China.  In order to establish a rapid, reliable and specific molecular detection method for M. vitis, the species-specific primers were designed with rDNA-ITS (ribosomal DNA internal transcribed spacer) gene fragment as the target.  The reaction system was optimized and the reliability, specificity and sensitivity of primer were testified, therefore, a rapid PCR detection method for M. vitis was established.  The result showed that the optimal annealing temperature of the primers was 53°C, which was suitable for the detection of different life stages of M. vitis.  Specificity test showed that the specific fragment size of 174 bp was obtained from M. vitis, but other five non-target nematodes did not have any amplification bands, thus effectively distinguish M. vitis and the other five species, and could specifically detect the M. vitis from mixed populations.  Sensitivity test showed that this PCR technique could detect the DNA of a single second-stage juvenile (J₂) and 10^–4 female.  Futhermore, this PCR technique could be used to detect directly M. vitis from soil samples.  The rapid, sensitive and specific PCR molecular detection technique could be used for the direct identification of a single J₂ of M. vitis and the detection of M. vitis in mixed nematode populations and the detection of two J₂s or one male in 0.5 g soil samples, which will provide technical support for the investigation of the occurrence and damage of M. vitis and the formulation of efficient green control strategies.     

Improved Nucleic Acid Spot Hybridization Technique for Detection of Potato Spindle Tuber Viroid (PSTVd)

Potato spindle tuber viroid (PSTVd) disease is one of the major diseases that threatens potato production. Therefore, an advanced, rapid and sensitive detection...     

Investigation of Aegilopsumbellulatafor stripe rust resistance,heading date,and the contents of iron,zinc, and gluten protein

Aegilops umbellulata (UU) is a wheat wild relative that has potential use in the genetic improvement of wheat.  In this study, 46 Ae. umbellulata accessions were investigated for stripe rust resistance, heading date (HD), and the contents of iron (Fe), zinc (Zn), and seed gluten proteins.  Forty-two of the accessions were classified as resistant to stripe rust, while the other four accessions were classified as susceptible to stripe rust in four environments.  The average HD of Ae. umbellulata was significantly longer than that of three common wheat cultivars (180.9 d vs. 137.0 d), with the exception of PI226500 (138.9 d).  The Ae. umbellulata accessions also showed high variability in Fe (69.74–348.09 mg kg^–1) and Zn (49.83–101.65 mg kg^–1) contents. Three accessions (viz., PI542362, PI542363, and PI554399) showed relatively higher Fe (230.96–348.09 mg kg^–1) and Zn (92.46–101.65 mg kg^–1) contents than the others.  The Fe content of Ae. umbellulata was similar to those of Ae. comosa and Ae. markgrafii but higher than those of Ae. tauschii and common wheat.  Aegilops umbellulata showed a higher Zn content than Ae. tauschii, Ae. comosa, and common wheat, but a lower content than Ae. markgrafii.  Furthermore, Ae. umbellulata had the highest proportion of γ-gliadin among all the species investigated (Ae. umbellulata vs. other species=mean 72.11% vs. 49.37%; range: 55.33–86.99% vs. 29.60–67.91%).  These results demonstrated that Ae. umbellulata exhibits great diversity in the investigated traits, so it can provide a potential gene pool for the genetic improvement of these traits in wheat.     

乌鲁木齐地区马铃薯纺锤块茎类病毒的检测与序列分析

根据马铃薯纺锤块茎类病毒(PSTVd)基因序列设计合成1对引物,对新疆乌鲁木齐地区马铃薯田间感病植株进行一步法RT-PCR检测,扩增出251 bp大小的目标片段,而健康植株无此扩增产物。将目的片段克隆到pGM-T载体上并进行序列测定,构建系统进化树分析各分离物间的分子差异性。结果表明马铃薯纺锤块茎类病毒乌鲁木齐分离物与国内外已报道毒株的核酸序列同源性达93.6%~99.2%。     

Biosynthesis of artemisinic acid in engineered Saccharomyces cerevisiae and its attractiveness to the mirid bug Apolygus lucorum

Artemisia annua is an important preferred host of the mirid bug Apolygus lucorum in autumn.Volatiles emitted from A.annua attract A.Iucorum.Volatile artemisinic acid of A.annua is a precursor of artemisinin that has been widely investigated in the Chinese herbal medicine field.However,little is known at this point about the biological roles of artemisinic acid in regulating the behavioral trends of A.lucorum.In this study,we collected volatiles from A.annua at the seedling stage by using headspa...     

Integrated pest management and plant health

Crop production and livelihoods of smallholder farmers are often threatened by crop insect pests and diseases worsening the insecurity of food.  Globalization has rapidly increased the introduction and threats of invasive pests.  Climate change results in a changed suitability of landscapes to pests, further increasing the threat and uncertainty of their impact.  Providing innovative technologies for sustainable pest management to smallholder farmers is urgently needed for food security and eliminating poverty.   The most devasting diseases and insect pests to major crops such as rice, wheat, maize and potato contribute to the largest yield losses in the world.  Under the support of the Food and Agriculture Organization (FAO), Chinese plant protection scientists, in collaboration with experts of different regions, carried out a specific project to prioritize top crop diseases and insect pests that affect smallholder farmers’ production globally.  After evaluation by relevant global experts, top 10 crop diseases and insect pests have been assessed as six crop diseases and four insect pests, namely cereal blast disease, potato late blight, wheat rust disease, Fusarium head blight, maize lethal necrosis disease, banana Fusarium wilt (TR4), rice planthopper, wheat aphid, whitefly, and oriental fruit fly.  Integrated pest management (IPM) guidelines for the identified diseases and insect pests have been formulated, and will be shared through a global knowledge platform.  To share the knowledge with more researchers, the IPM of four major diseases including cereal blast disease, Fusarium head blight, maize lethal necrosis disease and potato late blight were further reviewed and presented in this special focus.   The first case study is cereal blast disease caused by fungal pathogen Magnaporthe oryzae (Zhang et al. 2022), which is a destructive filamentous fungus that infects many plants including most economically important food crops, rice, wheat, pearl millet and finger millet (Chakraborty et al. 2021; Hossain 2022).  Different pathovars of M. oryzae often infect different host plants with high specificity.  The rice blast disease caused by the Oryza pathotype (MoO) of M. oryzae can result in 10–30% yield loss in rice-growing countries, posing a major threat to rice production, especially in the small-scale farming system (Mutiga et al. 2021).  The Triticum pathotype (MoT), causing wheat blast disease, was first found in Brazil in 1985.  It has now spread to other countries in South America, and also Asian countries such as Bangladesh (Islam et al. 2016).  Wheat blast disease can result in an average yield loss of 51% in the affected field, becoming one of the most fearsome wheat diseases (Islam et al. 2020).  Because of low fungicide efficacy against the blast diseases and lack of availability of resistant varieties, control of rice and wheat blast diseases is difficult.  A combination of management strategies including early detection and utilization of biopesticides was proposed (Zhang et al. 2022), providing some helpful insights for fighting these devasting cereal blast diseases.   The second case study is the fusarium head blight (FHB) caused by FHB pathogens, which are mainly the Fusarium graminearum species complex (Chen et al. 2022).  FHB is one of the most important diseases that affects wheat production worldwide (Summerell 2019).  In general, a severe FHB epidemic occurred every four or five years in the most of wheat production regions.  Since 2010, the outbreaks of FHB have become more frequent in China.  Besides causing yield loss in affected crop field, FHB also produces mycotoxin contaminating the harvested grains, which are harmful to humans and livestock (Stepien and Chelkowski 2010).  According to the economic importance and toxicity of FHB, F. graminearum is considered as one of the world’s top 10 fungal phytopathogens (Dean et al. 2012).  Breeding resistant cultivars has been considered as the most effective strategy against FHB (Wegulo et al. 2015).  Rational use of chemical pesticides, and potential biopesticides, and good agronomic practices are also important components in the IPM programme for FHB.    The third case study is the maize lethal necrosis disease (MLND), which is a relatively new viral disease on maize (Zhan et al. 2022).  The MLND is caused by the co-infection of maize chlorotic mottle virus (MCMV) and one of cereal-infecting potyviruses, and the symptoms on maize include leaf necrosis, premature aging, small cobs and even plant death (Redinbaugh and Stewart 2018).  First reported in Americas in 1970s and 1980s, the MLND has now spread to more than fifteen countries in the Americas, Asia and Africa (Wangai et al. 2012).  The outbreaks of MLND in several Asian and African countries caused devastating damage to maize production with large impacts on smallholder farmers (Mahuku et al. 2015).  Integrated management of MLND involves effective detection methods such as serological methods, nucleic acid-based methods, and next-generation sequencing.  The practices, such as using certified seeds, sanitary measures, crop rotation, and tolerant or resistant varieties, have been considered as the effective, economical and eco-friendly approach to prevent and control MLND. The fourth case study is the potato late blight (PLB) disease (Dong and Zhou 2022).  PLB, caused by the fungal-like oomycete pathogen Phytophthora infestans, is a devastating disease worldwide that led to the infamous Irish potato famine of the 1840s.  Besides the primary host potato, P. infestans also infects other solanaceous plants such as tomato, petunia and nightshade.  These infected plants can become pathogen inoculum to potato (Kirk et al. 2003).  Originated from Central Mexico or South America, this disease has spread to almost all major potato-producing countries including the United States, Canada, China, and India (Fry et al. 2015).  Up to now, PLB remains the most important biotic constraint to potato production worldwide and presents a major threat to global food security, especially for under-developed areas that heavily depend on potato as the major source of food (Cucak et al. 2021).  Careful agronomic practices, such as using pathogen-free seed, serve as the good start for the successful management of PLB.  Chemical fungicides remain the most effective means to control the pathogen.  However, these chemical fungicides should be used more scientifically to avoid over-dosage and high cost.  Some potential environmental-friendly biopesticides have been identified (He et al. 2021).  Additionally, new technologies which may bring some innovative solutions to control PLB are also proposed.   The desert locust (Schistocerca gregaria), the most destructive migratory insect pest in the world, was also selected in the special focus (Li et al. 2022).  Desert locust is an omnivorous insect, feeding on more than 300 various host plants including many cultivated crops and wild plants (Li et al. 2021).  Formation of desert locust swarms and the outbreak of desert locusts are induced by a combination of environmental stimuli.  During its outbreak and migration, desert locust can cause serious damage to cultivated crops, such as cotton, alfalfa, beans, wheat, barley, corn, flax, tobacco, tomato, potato, and melons, posing a major threat to food security and rural livelihoods.  Since the 20th century, there have been 15 outbreaks of the desert locust, affecting about 30 million km² of Africa and Asia continents and the lives of 850 million people in 65 countries (Ceccato et al. 2007; Divi 2020).  Studies demonstrate the correlation between poor early childhood health and the desert locust swarm outbreak (Kien and Nguyen 2022).  To date, much research has been conducted regarding the ecology and management of desert locusts.  Climate change resulted in more favorable conditions, which is a major factor contributing to the recent outbreak of desert locust in 2020 (Peng et al. 2020).  A critical component of preventive management programs is being able to locate significant infestations rapidly.  The FAO provides forecasts, early warning and alerts on the timing, scale and location of invasions and breeding through its global Desert Locust Information Service (DLIS).  Integrated management of desert locust, mainly including physical control methods, chemical insecticides, microbial pesticides, and biocontrol methods, are summarized in ths review (Li et al. 2022).   Occurrence of plant diseases and insect pests have been worsened by climate change in many aspects.  Prevention of yield loss of major crops is critical for achieving global food security.  Not only the IPM strategies should be adopted, but also the inter-government cooperation should be encouraged to share knowledge, information and innovative solutions, and to jointly tackle with challenges caused by transboundary pests.  All these efforts are needed to achieve the United Nations Sustainable Development Goals (SDGs) of 2030 Agenda for Sustainable Development.     

Transcriptional regulation of secondary metabolism and autophagy genes in response to DNA replication stress in Setosphaeriaturcica

The fungal pathogen Setosphaeria turcica causes northern corn leaf blight(NCLB), which leads to considerable crop losses. Setosphaeria turcica elaborates a specialized infection structures called appressorium for maize infection.Previously, we demonstrated that the S. turcica triggers an S-phase checkpoint and ATR(Ataxia Telangiectasia and Rad3 related)-dependent self-protective response to DNA genotoxic insults during maize infection. However, how the regulatory mechanism works was still largel...     

Expression profiling of transgenes (Cry1Ac and Cry2A) in cotton genotypes under different genetic backgrounds

Transgenic cotton carrying the CrylAc gene has revolutionized insect pest control since its adoption,although the development of resistance in insect pests has reduced its efficacy.After 10 years of cultivating Bacillus thuringiensis(Bt) cotton with a single Cry1 Ac gene,growers are on the verge of adopting Bt cotton that carries the double gene(Cry1 Ac+Cry2 A) due to its better effectiveness against insect pests.Thus,the current study was designed to evaluate the role of each gene in the effect...     

Changes in the activities of key enzymes and the abundance of functional genes involved in nitrogen transformation in rice rhizosphere soil under different aerated conditions

Soil microorganisms play important roles in nitrogen transformation.  The aim of this study was to characterize changes in the activity of nitrogen transformation enzymes and the abundance of nitrogen function genes in rhizosphere soil aerated using three different methods (continuous flooding (CF), continuous flooding and aeration (CFA), and alternate wetting and drying (AWD)).  The abundances of amoA ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), nirS, nirK, and nifH genes, and the activities of urease, protease, ammonia oxidase, nitrate reductase, and nitrite reductase were measured at the tillering (S1), heading (S2), and ripening (S3) stages.  We analyzed the relationships of the aforementioned microbial activity indices, in addition to soil microbial biomass carbon (MBC) and soil microbial biomass nitrogen (MBN), with the concentration of soil nitrate and ammonium nitrogen.  The abundance of nitrogen function genes and the activities of nitrogen invertase in rice rhizosphere soil were higher at S2 compared with S1 and S3 in all treatments.  AWD and CFA increased the abundance of amoA and nifH genes, and the activities of urease, protease, and ammonia oxidase, and decreased the abundance of nirS and nirK genes and the activities of nitrate reductase and nitrite reductase, with the effect of AWD being particularly strong.  During the entire growth period, the mean abundances of the AOA amoA, AOB amoA, and nifH genes were 2.9, 5.8, and 3.0 higher in the AWD treatment than in the CF treatment, respectively, and the activities of urease, protease, and ammonia oxidase were 1.1, 0.5, and 0.7 higher in the AWD treatment than in the CF treatment, respectively.  The abundances of the nirS and nirK genes, and the activities of nitrate reductase and nitrite reductase were 73.6, 84.8, 10.3 and 36.5% lower in the AWD treatment than in the CF treatment, respectively.  The abundances of the AOA amoA, AOB amoA, and nifH genes were significantly and positively correlated with the activities of urease, protease, and ammonia oxidase, and the abundances of the nirS and nirK genes were significantly positively correlated with the activities of nitrate reductase.  All the above indicators were positively correlated with soil MBC and MBN.  In sum, microbial activity related to nitrogen transformation in rice rhizosphere soil was highest at S2.  Aeration can effectively increase the activity of most nitrogen-converting microorganisms and MBN, and thus promote soil nitrogen transformation.      

Quantifying in situ N2 fluxes from an intensively managed calcareous soil using the 15N gas-flux method

Denitrification-induced nitrogen (N) losses from croplands may be greatly increased by intensive fertilization.  However, the accurate quantification of these losses is still challenging due to insufficient available in situ measurements of soil dinitrogen (N₂) emissions.  We carried out two one-week experiments in a maize–wheat cropping system with calcareous soil using the ¹⁵N gas-flux (¹⁵NGF) method to measure in situ N₂ fluxes following urea application.  Applications of ¹⁵N-labeled urea (99 atom%, 130–150 kg N ha⁻¹) were followed by irrigation on the 1st, 3rd, and 5th days after fertilization (DAF 1, 3, and 5, respectively).  The detection limits of the soil N₂ fluxes were 163–1 565, 81–485, and 54–281 μg N m⁻² h⁻¹ for the two-, four-, and six-hour static chamber enclosures, respectively.  The N₂ fluxes measured in 120 cases varied between 159 and 2 943 (811 on average) μg N m⁻² h⁻¹, which were higher than the detection limits, with the exception of only two cases.  The N₂ fluxes at DAF 3 were significantly higher (by nearly 80% (P<0.01)) than those at DAF 1 and 5 in the maize experiment, while there were no significant differences among the irrigation times in the wheat experiment.  The N₂ fluxes and the ratios of nitrous oxide (N₂O) to the N₂O plus N₂ fluxes following urea application to maize were approximately 65% and 11 times larger, respectively (P<0.01), than those following urea application to wheat.  Such differences could be mainly attributed to the higher soil water contents, temperatures, and availability of soil N substrates in the maize experiment than in the wheat experiment.  This study suggests that the ¹⁵NGF method is sensitive enough to measure in situ N₂ fluxes from intensively fertilized croplands with calcareous soils.     

基于锁式探针的番茄溃疡病菌实时荧光PCR快速检测

【目的】从口岸进境番茄种子中检测番茄溃疡病菌（Clavibacter michiganensis subsp. michiganensis,CMM）,一直以来都受检测周期的限制,快速、特异地从种子中检测该病原细菌需要新的方法。研究在锁式探针扩增方式上,选择连接酶依赖的PCR扩增方式,并结合实时荧光PCR技术,旨在建立番茄溃疡病菌基于锁式探针技术的实时荧光PCR快速检测方法,为口岸番茄种子快速检疫提供技术支持。【方法】根据番茄溃疡病菌的一段特异基因Pat-1序列,设计锁式探针的T1和T2臂,使之与CMM的特异性片段碱基序列互补,再按照锁式探针的设计原则设计锁式探针和扩增引物以及荧光探针。试验时,先将锁式探针与CMM以及参照菌株的DNA模板在DNA连接酶作用下分别进行环化连接,再用核酸外切酶Ⅰ和核酸外切酶Ⅲ消化未环化的线性锁式探针,最后以环化的锁式探针为模板,在扩增引物的作用下进行实时荧光PCR试验。建立CMM基于锁式探针技术的实时荧光PCR检测方法,分别比较该方法的特异性和灵敏度与常规PCR方法的差异,并用该方法对收集的来自日本、韩国和中国台湾的番茄种子以及国内采集的共45份样品进行检测。【结果】基于锁式探针技术的实时荧光PCR检测方法能够从供试的菌株中特异性地检出CMM,在供试的10种菌株中,只有靶标细菌能被特异性地检测到阳性,空白对照和其他参试菌株均没有荧光信号的增加,检测为阴性。比较该检测方法与常规PCR方法,其特异性和常规PCR方法一致。该检测方法检测灵敏度高,DNA最低浓度检测为50 fg•μL-1,而常规PCR方法检测DNA最低浓度为5 pg•μL-1,灵敏度高于常规PCR两个数量级。对收集的样品进行检测,结果显示,45份样品中共有5份样品CMM检测结果为阳性,分别是日本的番茄种子样品2份（编号Jap1214、Jap1102）,永泰采集的样品2份（编号为Yongt1001、Yongt1002）和闽清采集的样品1份（编号为Minq1001）。【结论】建立的基于锁式探针技术的荧光PCR方法具有高度的特异性和灵敏度,应用该检测方法对收集的进境番茄种子进行检测,可以直接从番茄种子中检测到CMM,该方法适合口岸番茄种子CMM的快速检测,有较好的口岸检疫实际应用价值。     

MicroRNA-370-5p inhibits pigmentation and cell proliferation by downregulating mitogen-activated protein kinase kinase kinase 8 expression in sheep melanocytes

In mammals, microRNAs (miRNAs) play key roles in multiple biological processes by regulating the expression of target genes.  Studies have found that the levels of miR-370-5p expression differ significantly in the skins of sheep with different hair colors; however, its function remains unclear.  In this study, we investigated the roles of miR-370-5p in sheep melanocytes and found that the overexpression of miR-370-5p significantly inhibited cell proliferation (P<0.01), tyrosinase activity (P=0.001) and significantly reduced (P<0.001) melanin production.  Functional prediction revealed that the 3´-untranslated region (UTR) of MAP3K8 has a putative miR-370-5p binding site, and the interaction between these two molecules was confirmed using luciferase reporter assays.  In situ hybridization assays revealed that MAP3K8 is expressed in the cytoplasm of melanocytes.  The results of quantitative RT-PCR and Western blotting analyses revealed that overexpression of miR-370-5p in melanocytes significantly inhibits (P<0.01) MAP3K8 expression via direct targeting of its 3´ UTR.  Inhibition of MAP3K8 expression by siRNA-MAP3K8 transfection induced a significant inhibition (P<0.01) of melanocyte proliferation and significant reduction (P<0.001) in melanin production, which is consistent with our observations for miR-370-5p.  Target gene rescue experiments indicated that the expression of MAP3K8 in melanocytes co-transfected with miR-370-5p and MAP3K8-cDNA (containing sites for the targeted binding to miR-370-5p) was significantly rescued (P≤0.001), which subsequently promoted significant increases in cell proliferation (P<0.001) and melanin production (P<0.01).  Collectively, these findings indicate that miR-370-5p plays a functional role in inhibiting sheep melanocyte proliferation and melanogenesis by downregulating the expression of MAP3K8.       

Multi-omics-driven development of alternative crops for natural rubber production

Natural rubber (NR) is an irreplaceable biopolymer of economic and strategic importance owing to its unique physical and chemical properties.  The Pará rubber tree (Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg.) is currently the exclusive commercial source of NR, and it is primarily grown in plantations restricted to the tropical and subtropical areas of Southeast Asia.  However, current Pará rubber production barely meets the sharply increasing global industrial demand for rubber.  Petroleum-based synthetic rubber (SR) has been used to supplement the shortage of NR but its industrial performance is not comparable to that of NR.  Thus, there is an urgent need to develop new productive rubber crops with broader environmental adaptability.  This review summarizes the current research progress on alternative rubber-producing plants, including horticultural plants (Taraxacum kok-saghyz Rodin and Lactuca L. species), woody plants (Parthenium argentatum A. Gray and Eucommia ulmoides Oliv.), and other plant species with potential for NR production.  With an emphasis on the molecular basis of NR biosynthesis revealed by a multi-omics approach, we highlight new integrative strategies and biotechnologies for exploring the mechanism of NR biosynthesis with a broader scope, which may accelerate the breeding and improvement of new rubber crops.      

Effects of LPA on the development of sheep in vitro fertilized embryos and attempt to establish sheep embryonic stem cells

Lysophosphatidic acid (LPA) is a small molecule glycerophospholipid, which regulates multiple downstream signalling pathways through G-protein-coupled receptors to achieve numerous functions on oocyte maturation and embryo development.  In this study, sheep in vitro fertilized embryos were applied to investigate the effects of LPA on early embryos development and embryonic stem cell establishment.  At first, the maturation medium containing estrus female sheep serum and synthetic oviduct fluid (SOF) were optimized for sheep IVF, and then the effects of LPA were investigated.  From 0.1 to 10 μmol L^–1, LPA had no significant effect on the cleavage rate (P>0.05), but the maturation rate and blastocyst rate increased dependently with LPA concentration (P<0.05), and the blastocyst morphology was normal.  When the LPA concentration was 15 μmol L^–1, the maturation rate, cleavage rate and blastocyst rate decreased significantly (P<0.05), and the blastocyst exhibited abnormal morphology and could not develop into high-quality blastocyst.  Besides, the exogenous LPA increases the expression of LPAR2, LPAR4, TE-related gene CDX-2 and pluripotency-related gene OCT-4 in sheep early IVF embryos with the raise of LPA concentration from 0.1 to 10 μmol L^–1.  The expression of LPAR2, LPAR4, CDX-2 and OCT-4 from the LPA-0.1 μmol L^–1 to LPA-10 μmol L^–1 groups in early embryos were extremely significant (P<0.05), while the expression of these genes significantly decreased in 15 μmol L^–1 LPA-treated embryos compared with LPA-10 μmol L^–1 group (P<0.05).  The inner cell mass in 15 μmol L^–1 LPA-treated embryos was also disturbed, and the blastocysts formation was abnormal.  Secondly, the sheep IVF blastocysts were applied to establish embryonic stem cells.  The results showed that LPA made the blastocyst inoculated cells grow towards TSC-like cells.  They enhanced the fluorescence intensity and mRNA abundance of OCT-4 and CDX-2 as the concentration increased from 0 to 10 μmol L^–1, while 15 μmol L^–1 LPA decreased OCT-4 and CDX-2 expression in the derived cells.  The expression of CDX-2 and OCT-4 in the blastocyst inoculated cells of LPA-1 μmol L^–1 group and LPA-10 μmol L^–1 group extremely significantly increased (P<0.05), but there was significant decrease in LPA-15 μmol L^–1 group compared with LPA-10 μmol L^–1 group (P<0.05).  Meanwhile, the protein expression of LPAR2 and LPAR4 remarkably increased after treatment of LPA at 10 μmol L^–1 concentration.  This study references the IVF embryo production and embryonic stem cell research of domestic animals.      

dep1 improves rice grain yield and nitrogen use efficiency simultaneously by enhancing nitrogen and dry matter translocation

The rice cultivars carrying dep1(dense and erect panicle 1) have the potential to achieve both high grain yield and high nitrogen use efficiency(NUE). However, few studies have focused on the agronomic and physiological performance of those cultivars associated with high yield and high NUE under field conditions. Therefore, we evaluated the yield performance and NUE of two near-isogenic lines(NILs) carrying DEP1(NIL-DEP1) and dep1-1(NIL-dep1) genes under the Nanjing 6 background at 0 and 120 kg ...     

用小RNA深度测序鉴定广西冬种马铃薯病毒

【目的】对广西冬种马铃薯病毒进行鉴定,为无病毒种薯选择和大田防治提供依据。【方法】2012年在马铃薯主要产区采集具有明显病毒病症状的样品,在血清学ELISA检测的基础上,进一步用小RNA深度测序对按症状分类的样品进行混合样本的病毒种类鉴定,再用RT-PCR方法对分组混合样本进行验证。【结果】在109个样本中检测到马铃薯卷叶病毒（Potato leafroll virus,PLRV）、马铃薯A病毒（Potato virus A,PVA）、马铃薯H病毒（Potato virus H,PVH）、马铃薯M病毒（Potato virus M,PVM）、马铃薯S病毒（Potato virus S,PVS）、马铃薯Y病毒（Potato virus Y,PVY）和马铃薯纺锤块茎类病毒（Potato spindle tuber viroid,PSTVd）,同时发现PVS有丰富的株系分化。【结论】近年广西冬种马铃薯病毒种类增多,病症多样,亟需加强种薯管理,培育无毒健康种薯。